Physical sensors are used in many modern machines to measure and monitor physical phenomena, such as temperature, speed, and fluid flow constituents. Physical sensors often take direct measurements of the physical phenomena and convert these measurements into measurement data to be further processed by control systems. Many physical sensors have specification ranges within which the physical sensor is calibrated to measure data accurately. Moreover, the specification range may vary from sensor to sensor. For example, different temperature sensors may have specification ranges of −40-100° C., 200-500° C., 250-700° C., etc. Likewise, different emissions sensors, pressure sensors, accelerometers, etc., may have their own specification ranges.
In applications, such as monitoring, e.g., emissions of a machine, temperature of various components, airflows, fluids, etc. of a machine, or any other property associated with a machine, multiple different sensors may be used based on the range of values being measured. In the temperature monitoring example, temperatures sensors may be needed such that each temperature sensor has a specification range that covers the corresponding expected range of temperature to be measured. Thus, an organization that manufactures or operates the machine may have to source multiple different temperature sensors based on the different ranges of temperatures being measured, increasing logistical complexity and cost. Moreover, in some applications the expected range of temperatures to be measured may be larger than the specification range of a reasonably-priced sensor. In these instances, a more expensive sensor may increase the overall cost of the machine.
Instead of direct measurements, virtual sensors are developed to process other physically measured values and to produce values that were previously measured directly by physical sensors. For example, U.S. Pat. No. 5,386,373 (the '373 patent) issued to Keeler et al. on Jan. 31, 1995, discloses a virtual continuous emission monitoring system with sensor validation. The system of the '373 patent compares a difference between an actual sensor output and a predicted sensor output to a threshold value. If the difference exceeds a threshold value, the system may replace the actual sensor output with the predicted sensor output, and control the system based on the predicted sensor output. The techniques disclosed in the '373 patent may protect against a faulty sensor. However, the techniques of the '373 patent may only calculate a difference between an actual sensor output and a predicted sensor output, and, as such, may be incapable of extending a range of a physical sensor using a virtual sensor.
The disclosed methods and systems are directed to solving one or more of the problems set forth above and/or other problems of the prior art.